Method and device for synchronization

ABSTRACT

A method for synchronization in a wireless system is disclosed. In the method, at least one bit is included in a physical broadcast channel (PBCH), wherein one or more bits of the at least one bit indicates a location of a slot group comprising at least one synchronization signal block in a synchronization signal burst set and/or additional system information.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2018/099850, filed Aug. 10, 2018, which claims the benefit ofInternational Application No. PCT/CN2017/097282, filed Aug. 11, 2017,which are all hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure relates generally to wireless communicationtechnology, and in particular, to a method for synchronization in awireless system and related device.

BACKGROUND

In order to connect to a network, a terminal device needs to acquirenetwork synchronization information and obtain essential systeminformation. Synchronization signals (SSs) are used for adjusting thefrequency of the terminal device relative to the network, and forfinding proper timing of the received signal from the network.

In the New Radio (NR) system, a procedure for synchronization and accessmay involve several signals as follows:

NR-Primary synchronization signal (NR-PSS) that allows for networkdetection in the presence of a high initial frequency error, up to tensof ppm. Additionally, NR-PSS provides a network timing reference. 3GPPhas selected Zadoff-Chu sequences as PSS signals in a Long TermEvolution (LTE) system and m-sequence in the NR system.

NR-Secondary synchronization signal (NR-SSS) that allows for moreaccurate frequency adjustments and channel estimation while at the sametime providing fundamental network information, e.g. cell identifier(ID).

NR-Physical broadcast channel (NR-PBCH) that provides a subset ofminimum system information. It will also provide timing informationwithin a cell, e.g. to separate timing between beams transmitted from acell. The amount of information to fit into the NR-PBCH is of coursehighly limited to keep the size down. Furthermore, demodulationreference signals (DMRS) are interleaved with NR-PBCH resources in orderto receive.

A synchronization signal block (SSB) as proposed for the NR system maycomprise the above signals NR-PSS, NR-SSS, NR-PBCH and related DMRS.FIG. 1 shows an illustration of the SSB in which the NR-PBCH is a partof the SSB. In the illustration, two OFDM symbols are reserved forNR-PBCH transmission. The NR-PSS and NR-SSS are defined to be 127subcarriers wide whereas the NR-PBCH is defined to be 288 subcarrierswide.

A number of SS blocks that are typically close in time constitute an SSburst set. The SS burst set may be repeated periodically, e.g. every 20ms in default. The terminal device can, by using the SS blocks in the SSburst set, determine downlink timing and frequency offset, and acquiresome fundamental system information from the NR-PBCH. It has been agreedthat an NR UE in idle mode can expect an SS burst set transmitted onceper 20 ms, and the NR UE in connected mode can expect the SS burst setsonce per 5 ms. Hence, once the NR UE has obtained downlinksynchronization, it knows in which slots to expect the SS blocktransmissions. The location of the SS block in a SS burst set needs tobe provided to the NR UE to derive the subframe level synchronization.

SUMMARY

It is therefore an object of embodiments of the present disclosure toprovide a method for synchronization in a wireless system which canindicate the location of the SS block in the SS burst set as well asadditional system information.

According to a first aspect of the disclosure, there is provided amethod performed in a base station for synchronization in a wirelesssystem. The method comprises transmitting a physical broadcast channel(PBCH) including one or more bits. The one or more bits indicates alocation of a slot group comprising at least one synchronization signalblock in a synchronization signal burst set and/or additional systeminformation. In particular, the one or more bits indicate additionalsystem information if a frequency of the wireless system is within afrequency range up to a predefined frequency e.g. 6 GHz. Otherwise, i.e.if the frequency of the wireless system is above the predefinedfrequency, the one or more bits indicate the location of the slot groupcomprising at least one synchronization signal block in thesynchronization signal burst set including the slot group.

In some embodiments, the PBCH may be interleaved with a downlink pilotsignal sequence which carries one or more bits indicating a location ofthe at least one synchronization signal block within the slot group.

In some embodiments, the additional system information comprises atleast one of: a frame number offset of a coexisting system relative tothe wireless system, system information of a neighbor cell in thecoexisting system, configuration information of the synchronizationsignal burst set of a neighbor cell in the wireless system, and anindication related to synchronization information in the wirelesssystem.

In some embodiments, the system information of a neighbor cell in thecoexisting system comprises an identifier of the neighbor cell.

In some embodiments, the configuration information of thesynchronization signal burst set of a neighbor cell in the NR systemcomprises the number of the synchronization signal blocks actuallytransmitted in the neighbor cell and periodicity of the synchronizationsignal burst set.

According to a second aspect of the disclosure, there is provided a basestation in a wireless system. The base station comprises a processor,and a memory. The memory contains instructions executable by theprocessor, whereby the base station is operative to perform the methodaccording to the first aspect of the disclosure.

According to a third aspect of the disclosure, there is provided acomputer readable storage medium having a computer program storedthereon. The computer program is executable by a base station to causethe base station to carry out the above method for synchronization in awireless system according to the first aspect of the disclosure.

According to a fourth aspect of the disclosure, there is provided amethod performed in a terminal device for synchronization in a wirelesssystem. The method comprises receiving a PBCH including one or more bitsfrom a base station. The one or more bits indicate a location of a slotgroup comprising at least one synchronization signal block in asynchronization signal burst set and/or additional system information.Then the location of the slot group in the synchronization signal burstset and/or the additional system information are obtained from the oneor more bits. In particular, the one or more bits indicate theadditional system information if a frequency of the wireless system iswithin a frequency range up to a predefined frequency, e.g. 6 GHz.Otherwise, if the frequency of the wireless system is above thepredefined frequency, the one or more bits indicate the location of theslot group comprising at least one synchronization signal block in thesynchronization signal burst set including the slot group.

According to a fifth aspect of the disclosure, there is provided aterminal device in a wireless system. The terminal device comprises aprocessor and a memory. The memory contains instructions executable bythe processor, whereby the terminal device is operative to perform themethod for synchronization according to the fourth aspect of thedisclosure.

It is an advantage that the method for synchronization can indicate thelocations of the SS blocks as well as the additional system informationin the PBCH, especially in the NR-PBCH, thereby greatly reducing networkdetection of a terminal device.

BRIEF DESCRIPTION OF DRAWINGS

Through the more detailed description of some embodiments of the presentdisclosure in the accompanying drawings, the above and other objects,features and advantages of the present disclosure will become moreapparent, wherein the same reference generally refers to the samecomponents in the embodiments of the present disclosure.

FIG. 1 is a diagram showing an illustration of the SSB;

FIG. 2 is a diagram illustrating the SS burst set;

FIG. 3 is a diagram illustrating the method for synchronizationaccording to some embodiments of the present disclosure;

FIG. 4 is a diagram illustrating an example of payload of the NR-PBCHaccording to some embodiment of the present disclosure;

FIG. 5 is a diagram illustrating an example of the indication of thelocations of the SS blocks according to some embodiments of the presentdisclosure;

FIG. 6 is a diagram illustrating the system frame number offset in thecoexistence of the NR system and LTE system;

FIG. 7 is a schematic block diagram of a network device according tosome embodiments of the present disclosure;

FIG. 8 is a schematic block diagram of a network device according tosome embodiments of the present disclosure;

FIG. 9 is a diagram illustrating the method for synchronizationaccording to some embodiments of the present disclosure; and

FIG. 10 is a schematic block diagram of a terminal device according tosome embodiments of the present disclosure.

DETAILED DESCRIPTION

Some preferable embodiments will be described in more detail withreference to the accompanying drawings, in which the preferableembodiments of the present disclosure have been illustrated. However,the present disclosure can be implemented in various manners, and thusshould not be construed to be limited to the embodiments disclosedherein. On the contrary, those embodiments are provided for the thoroughand complete understanding of the present disclosure, and completelyconveying the scope of the present disclosure to those skilled in theart.

Currently in 3GPP, it has been agreed that the transmission of the SSblocks within the SS burst set is confined to a 5 ms window regardlessof a periodicity of the SS burst set. Within this 5 ms window, thenumber of locations of possible candidate SS blocks is L. Therefore themaximum number of the SS blocks within the SS burst set L is differentfor different frequency ranges. For a frequency range up to 3 GHz (i.e.≤3GHz), L is 4. For a frequency range from 3 GHz to 6 GHz (i.e. 3GHz<the frequency≤3 GHz), L is 8. For a frequency range from 6 GHz to52.6 GHz (i.e. 6 GHz<the frequency≤52.6 GHz), L is 64. Note that it isassumed that the minimum number of the SS blocks within each SS burstset is one to define performance requirements. The SS burst set is asshown in FIG. 2. The blocks with a gray scale represents the slots fortransmitting the SS blocks. “15 kHz”, “30 kHz”, “120 kHz” and “240 kHz”as shown in FIG. 2 refer to the subcarrier spacing.

Further it has been agreed that some bits of a SS block time index whichindicates the locations of the SS blocks are carried by changing theDMRS sequence within each 5 ms period. Scrambling sequence of the PBCHmay or may not carry a part of timing information. The remaining bits ofthe SS block time index may be carried explicitly in the NR-PBCHpayload. Therefore, it has been agreed to deliver the SS block timeindex by the NR-PBCH transmission using an implicit approach by the DMRSsequence and explicit bits in the NR-PBCH payload.

There are following problems to indicate the SS block time index by thisway:

1. The total numbers of bits of the SS block time index are differentfor different frequency ranges;

2. The NR-PBCH payload size should be defined and constant for allfrequency ranges;

3. There will be different requirements on the number of the explicitbits in the NR-PBCH payload for different frequency ranges.

In summary, the number of the explicit bits for the higher frequencyrange would be larger than that for the lower frequency range.

In view of the above problems, a new method for synchronization in awireless system is proposed. FIG. 3 shows a diagram illustrating themethod for synchronization according to some embodiments of the presentdisclosure. In some embodiments of the present disclosure, the methodmay be performed by a network device in the wireless system. Thewireless system may be for example the NR system, and the network devicemay be a base station, e.g. gNodeB, in the NR system.

As shown in FIG. 3, at block 310, the network device may include atleast one bit in the PBCH, particularly the NR-PBCH in the NR system.One or more bits of the at least one bit may indicate a location of aslot group comprising at least one SS block in a SS burst set and/oradditional system information. In particular, the network devicetransmits the PBCH including the one or more bits to a terminal device.The one or more bits indicate the additional system information if afrequency of the wireless system is within a frequency range up to apredefined frequency, e.g. 6 GHz. Otherwise, if the frequency is abovethe predefined frequency, the one or more bits indicate the location ofthe slot group comprising the at least one SS block in thesynchronization signal burst set including the slot group.

In some embodiments, one or more bits of the at least one bit mayindicate a location of the at least one SS block within the slot group.In such embodiments, the one or more bits may be carried by differentdownlink pilot signal sequences, e.g. the DMRS sequences.

As described above, the SS burst set may comprise multiple SS blocks.For the frequency range up to 3 GHz, the SS burst set may comprise 4 SSblocks. For the frequency range from 3 GHz to 6 GHz, the SS burst setmay comprise 8 SS blocks. For the frequency range from 6 GHz to 52.6GHz, the SS burst set may comprise 64 SS blocks. In some embodiments, itis assumed that a slot group comprises continuous four slots for thefrequency range from 3 GHz and comprises continuous 2 slots for thefrequency range up to 3 GHz, and that each slot may contain at most twoSS blocks, for example. Therefore, for the frequency range up to 3 GHz,the SS burst set may comprise one slot group, and each slot of the oneslot group comprises 2 SS blocks, so the SS burst set comprises 4 SSblocks (i.e. L=4). For the frequency range from 3 GHz to 6 GHz, the SSburst set may comprise one slot group and each slot of the slot groupmay comprise 2 SS blocks, so the SS burst set comprises 8 SS blocks(i.e. L=8). For the frequency range from 6 GHz to 52.6 GHz, the SS burstset may comprise eight slot groups, and each of the eight slot groupsmay comprise 8 SS blocks, so the SS burst set comprises 64 SS blocks(i.e. L=64). A person skilled in the art will appreciate that the slotgroup may be consisted of any other number of slots.

Next an example in which the method for synchronization is implementedfor all frequency ranges will be described in detail. This example isapplied in the NR system. In this example, the NR-PBCH may include 6bits indicative of the locations of the SS blocks in the SS burst set.Three bits of the 6 bits may be used to indicate the location of theslot group in the SS burst set and/or additional system information, andmay be included in a payload of the NR-PBCH. In the following, the bitsin the payload of the NR-PBCH may be also referred to as “explicitbits”. The other 3 bits may be used to indicate the locations of the SSblocks within the slot group, and may be carried by the DMRS sequences.Referring to FIG. 4, three explicit bits s(0), s(1), s(2) to indicatethe location of the slot group and/or the additional system informationare attached with MIB (Master Information Block) from higher layer andL1 payload to constitute the payload of the NR-PBCH.

In the case of the frequency range less than 6 GHz, the maximum numberof the SS blocks in the SS burst set is eight. So the locations of theSS blocks may be indicated by using the DMRS sequence only. Theremaining 3 explicit bits may be used to indicate the additional systeminformation, which will be described later.

In the case of the frequency range higher than 6 GHz, the maximum numberof the SS blocks in the SS burst set is 64. All the six bits are used toindicate the locations of the SS blocks. In this case, the threeexplicit bits in the payload of the NR-PBCH may indicate the locationsof the eight slot groups, and the three bits carried by the differentDMRS sequences may implicitly indicate the locations of the eight SSblocks within the slot group, as shown in FIG. 5.

Although the example in which the bits carried by the DMRS sequences are3 bits and the explicit bits in the payload of the NR-PBCH are 3 bitshas been described above, a person skilled in the art will appreciatethat the bits carried by the DMRS sequences may be 2 bits and theexplicit bits in the payload of the NR-PBCH may be 4 bits.

In addition, a person skilled in the art will also appreciate that thenumber of bits in the NR-PBCH may be more than 6 bits. In this case, thebits other than those indicative of the locations of the SS blocks mayindicate the additional system information.

In some embodiments, the bits carried by the DMRS sequences may indicatethe location of a slot group comprising at least one SS block in a SSburst set, and the explicit bits in the payload of the NR-PBCH mayindicate the location of the SS block within the slot group and/or theadditional system information.

In some embodiments, the additional system information may comprise aframe number offset of a coexisting system relative to the wirelesssystem. In the case that the wireless system is the NR system, thecoexisting system may be the LTE system. In the two systems, the framedurations are defined as 10 ms, and may have different frame number asillustrated in FIG. 6. In FIG. 6, the frame number in the LTE system isdenoted by n_(sfn) ^((LTE)), and the frame number in the NR system inthe same time duration is denoted by n_(sfn) ^((NR)). Since almost allthe data transmissions, especially the system information, are based onthe frame number, the exact frame number will make much more sense for aterminal device such as NR user equipment. Thus, the frame number offsetbetween the two systems, i.e. n_(sfn) ^((NR))−n_(sfn) ^((LTE)) may beindicated by the explicit bits. Dependent on the number of the explicitbits, the frame number offset is within a range, such as 8 frames forthree explicit bits, and more frames for more explicit bits.

In some embodiments, the additional system information may comprisesystem information of a neighbor cell in the coexisting system. Such thesystem information may comprise an identifier of the neighbor cell, e.g.a target cell.

In the LTE system, there are 504 unique physical-layer cell identities.The physical-layer cell identities may be grouped into 168 uniquephysical-layer cell-identity groups, each group containing three uniqueidentities. The grouping is such that each physical-layer cell identityis a part of one and only one physical-layer cell-identity group. Thus aphysical-layer cell identity may be uniquely defined by N_(ID)^(cell)=3N_(ID) ⁽¹⁾+N_(ID) ⁽²⁾, wherein the number N_(ID) ⁽¹⁾ is in therange of 0 to 167, representing the physical-layer cell-identity group,and the number N_(ID) ⁽²⁾ is in the range of 0 to 2, representing thephysical-layer identity within the physical-layer cell-identity group.

In this case, the three explicit bits can be used to indicate presenceof one or more neighbor cells of the coexisting LTE system, with thephysical-layer identity 0, 1 or 2 within the physical-layercell-identity group in the neighborhood (coverage area) of the currentserving cell as shown in Table 1.

TABLE 1 Explicit Bits N_(ID) ⁽²⁾ of neighbor cell(s) 000 No LTE systemcoexisting 001 {0} 010 {1} 100 {2} 011 {0, 1} 101 {0, 2} 110 {1, 2} 111{0, 1, 2}

In some embodiments, the additional system information may compriseconfiguration information of the SS burst set of a neighbor cell in thewireless system. For example, such configuration information maycomprise the number of the synchronization signal blocks actuallytransmitted in the neighbor cell and periodicity of the synchronizationsignal burst set.

In the case of the frequency range less than 6 GHz, the maximum number Lof the SS blocks is 8 or 4, and the candidate locations for the actualSS block(s) transmission need to be pre-defined as a set to avoidarbitrary allocation. For example, the locations may be defined as thecontinuous N (N≤L) blocks in the SS burst set, such that there are only2, 3 and 6 (for the frequency range higher than 6 GHz) bits needed forall the three frequency ranges.

Therefore three explicit bits may be defined as below to indicate thenumber of actual transmitted SS blocks for one NR neighbor cell (ifexisted) with maximum number of actual transmitted SS blocks among allthe neighbor NR cell(s) or the number of actual transmitted SS blocks ofa neighbor cell as the target cell:

“000” indicates the maximum 1 SS block in the cell(s) is actuallytransmitted;

“001” indicates the maximum 2 SS blocks in the cell(s) are actuallytransmitted;

“010” indicates the maximum 3 SS blocks in the cell(s) are actuallytransmitted;

“100” indicates the maximum 4 SS blocks in the cell(s) are actuallytransmitted;

“011” indicates the maximum 5 SS blocks in the cell(s) are actuallytransmitted;

“101” indicates the maximum 6 SS blocks in the cell(s) are actuallytransmitted;

“110” indicates the maximum 7 SS blocks in the cell(s) are actuallytransmitted; and

“111” indicates the maximum 8 SS blocks in the cell(s) are actuallytransmitted.

In some embodiments, the additional system information may comprise anindication related to synchronization information in the wirelesssystem. In addition, a person skilled in the art will appreciate thatthe additional system information may be any combination of the abovedescribed system information.

It can be seen from the above description that the method forsynchronization according to the above embodiments can indicate thelocations of the SS blocks as well as the additional system informationin the NR-PBCH. Moreover the same number of the explicit bits may beused for all the frequency ranges for the wireless system, especiallythe NR system. The explicit bits can be used to indicate the additionalsystem information, other than indicating the part of the locations.

FIG. 7 is a schematic block diagram of the network device 700 accordingto some embodiments of the present disclosure. The network device 700may be a base station in the wireless system, e.g. gNodeB in the NRsystem. As shown in FIG. 7, the network device 700 may comprise aprocessor 701 and a memory 702. The memory 702 may contain instructionsexecutable by the processor 701. The network device 700 is operative toinclude at least one bit in a PBCH, one or more bits of the at least onebit indicating a location of a slot group comprising at least onesynchronization signal block in a synchronization signal burst setand/or additional system information. In particular, the network device700 is operative to transmit the PBCH including the one or more bits.The one or more bits indicate the additional system information if afrequency of the wireless system is within a frequency range up to apredefined frequency, e.g. 6 GHz. Otherwise if the frequency of thewireless system is above the predefined frequency, the one or more bitsindicate the location of the slot group comprising the at least one SSblock in the SS burst set including the slot group.

The processor 701 may be of any type suitable to the local technicalenvironment, and may comprise one or more of general purpose computers,special purpose computers, microprocessors, digital signal processors(DSPs) and processors based on multi-core processor architectures, asnon-limiting examples. The memory 702 may be of any type suitable to thelocal technical environment and may be implemented using any suitabledata storage technology, such as semiconductor based memory devices,flash memory, magnetic memory devices and systems, optical memorydevices and systems, fixed memory and removable memory.

In some embodiments, the network device 700 may further comprise atransceiver 703 operative to transmit signals to and receive signalsfrom a wireless terminal, and a network interface 704 operative tocommunicate signals with backend network elements.

According to some embodiments of the present disclosure, a networkdevice 800 for synchronization is provided. As shown in FIG. 8, thenetwork device 800 may be a base station, e.g. gNodeB, in the NR system.The network device may comprise a transmitting module 801 operable toinclude at least one bit in a physical broadcast channel (PBCH), one ormore bits of the at least one bit indicating a location of a slot groupcomprising at least one synchronization signal block in asynchronization signal burst set and/or additional system information.

It should be noted that FIG. 8 merely illustrates various functionalmodules in the network device 800, and a person skilled in the art canimplement these functional modules in practice using any suitablesoftware and hardware. Thus the embodiments herein are generally notlimited to the shown structure of the network device 800 and functionalmodules.

In some embodiments of the present disclosure, there is also provided acomputer readable storage medium having a computer program storedthereon. The computer program is executable by a device to cause thedevice to carry out the above method for synchronization.

According to some embodiments of the present disclosure, a methodperformed in a terminal device for synchronization in a wireless systemis further provided. As shown in FIG. 9, at block 910, at least one bitin a PBCH is received from a network device. One or more bits of the atleast one bit indicates a location of a slot group comprising at leastone synchronization signal block in a synchronization signal burst setand/or additional system information. In particular, the terminal devicereceives the PBCH including the one or more bits from a base station.The one or more bits indicate additional system information if afrequency of the wireless system is within a frequency range up to apredefined frequency e.g. 6 GHz. Otherwise, if the frequency of thewireless system is above the predefined frequency, the one or more bitsindicate the location of the slot group comprising the at least one SSblock in the SS burst set including the slot group. Then at block 920,the location of the slot group in the synchronization signal burst setand/or the additional system information are obtained from the at leastone bit.

In some embodiments, one or more bits of the at least one bit indicate alocation of the at least one synchronization signal block within theslot group. In the method, the location of the at least onesynchronization signal block within the slot group are obtained from theone or more bits.

In some embodiments, the wireless system is a NR system.

According to some embodiments of the disclosure, a terminal device 1000in a wireless system is further provided. As shown in FIG. 10, theterminal device 1000 comprises a processor 1011, and a memory 1012. Thememory 1012 contains instructions executable by the processor 1011,whereby the terminal device is operative to perform the method forsynchronization as described with regard to FIG. 9. The terminal device1000 may be a radio device, such as a mobile phone, a wearable device, atablet, etc., a vehicle with radio communication functionality, or anyother type of electronic device with radio communication functionality.

In general, the various exemplary embodiments may be implemented inhardware or special purpose circuits, software, logic or any combinationthereof. For example, some aspects may be implemented in hardware, whileother aspects may be implemented in firmware or software that may beexecuted by a controller, microprocessor or other computing device,although the disclosure is not limited thereto. While various aspects ofthe exemplary embodiments of this disclosure may be illustrated anddescribed as block diagrams, flow charts, or using some other pictorialrepresentation, it is well understood that these blocks, apparatus,systems, techniques or methods described herein may be implemented in,as non-limiting examples, hardware, software, firmware, special purposecircuits or logic, general purpose hardware or controller or othercomputing devices, or some combination thereof.

As such, it should be appreciated that at least some aspects of theexemplary embodiments of the disclosure may be practiced in variouscomponents such as integrated circuit chips and modules. It should thusbe appreciated that the exemplary embodiments of this invention may berealized in an apparatus that is embodied as an integrated circuit,where the integrated circuit may comprise circuitry (as well as possiblyfirmware) for embodying at least one or more of a data processor, adigital signal processor, baseband circuitry and radio frequencycircuitry that are configurable so as to operate in accordance with theexemplary embodiments of this disclosure.

It should be appreciated that at least some aspects of the exemplaryembodiments of the disclosure may be embodied in computer-executableinstructions, such as in one or more program modules, executed by one ormore computers or other devices. Generally, program modules compriseroutines, programs, objects, components, data structures, etc. thatperform particular tasks or implement particular abstract data typeswhen executed by a processor in a computer or other device. The computerexecutable instructions may be stored on a computer readable medium suchas a hard disk, optical disk, removable storage media, solid statememory, RAM, etc. As will be appreciated by those skilled in the art,the functionality of the program modules may be combined or distributedas desired in various embodiments. In addition, the functionality may beembodied in whole or in part in firmware or hardware equivalents such asintegrated circuits, field programmable gate arrays (FPGA), and thelike.

The present disclosure comprises any novel feature or combination offeatures disclosed herein either explicitly or any generalizationthereof. Various modifications and adaptations to the foregoingexemplary embodiments of this disclosure may become apparent to thoseskilled in the relevant arts in view of the foregoing description, whenread in conjunction with the accompanying drawings. However, any and allmodifications will still fall within the scope of the non-limiting andexemplary embodiments of this disclosure.

What is claimed is:
 1. A method in a base station for synchronization ina wireless system comprising: transmitting a physical broadcast channel(PBCH) including one or more bits, wherein the one or more bits indicateadditional system information if a frequency of the wireless system iswithin a frequency range up to a predefined frequency and otherwiseindicate a location of a slot group comprising at least onesynchronization signal block in a synchronization signal burst setincluding the slot group.
 2. The method according to claim 1 wherein thePBCH is interleaved with a downlink pilot signal sequence which carriesone or more bits indicating a location of the at least onesynchronization signal block within the slot group.
 3. The methodaccording to claim 1, wherein the additional system informationcomprises a frame number offset of a coexisting system relative to thewireless system.
 4. The method according to claim 1, wherein theadditional system information comprises system information of a neighborcell in a coexisting system.
 5. The method according to claim 4 whereinthe system information of a neighbor cell in the coexisting systemcomprises an identifier of the neighbor cell.
 6. The method according toclaim 1, wherein the additional system information comprisesconfiguration information of a synchronization signal burst set of aneighbor cell in the wireless system, and an indication related tosynchronization information in the wireless system.
 7. The methodaccording to claim 6 wherein the configuration information of thesynchronization signal burst set of the neighbor cell in the wirelesssystem comprises a number of the synchronization signal blocks actuallytransmitted in the neighbor cell and periodicity of the synchronizationsignal burst set.
 8. The method according to claim 1 wherein the one ormore bits are included in a payload of the PBCH and wherein the one ormore bits are the most significant bits of the payload.
 9. The methodaccording to claim 1 wherein the predefined frequency is 6 GHz.
 10. Abase station in a wireless system comprising: a processor; and a memory,the memory containing instructions which, when executed by theprocessor, cause the base station to: transmit a physical broadcastchannel (PBCH) including one or more bits, wherein the one or more bitsindicate additional system information if a frequency of the wirelesssystem is within a frequency range up to a predefined frequency andotherwise indicate a location of a slot group comprising at least onesynchronization signal block in a synchronization signal burst setincluding the slot group.
 11. The base station according to claim 10,wherein the PBCH is interleaved with a downlink pilot signal sequencewhich carries one or more bits indicating a location of the at least onesynchronization signal block within the slot group.
 12. A method in aterminal device for synchronization in a wireless system comprising:receiving a physical broadcast channel (PBCH) including one or more bitsfrom a base station, wherein the one or more bits indicate additionalsystem information if a frequency of the wireless system is within afrequency range up to a predefined frequency and otherwise indicate alocation of a slot group comprising at least one synchronization signalblock in a synchronization signal burst set including the slot group;and obtaining from the one or more bits the location of the slot groupin the synchronization signal burst set or the additional systeminformation.
 13. The method according to claim 12, wherein the PBCH isinterleaved with a downlink pilot signal sequence carrying one or morebits indicating a location of the at least one synchronization signalblock within the slot group; and the method further comprises obtainingfrom the downlink pilot signal sequence the location of the at least onesynchronization signal block within the slot group.
 14. The methodaccording to claim 12, wherein the additional system informationcomprises a frame number offset of a coexisting system relative to thewireless system.
 15. The method according to claim 12 wherein theadditional system information comprises system information of a neighborcell in a coexisting system.
 16. The method according to claim 15wherein the system information of a neighbor cell in the coexistingsystem comprises an identifier of the neighbor cell.
 17. The methodaccording to claim 12 wherein the additional system informationcomprises configuration information of the synchronization signal burstset of a neighbor cell in the wireless system.
 18. The method accordingto claim 17 wherein the configuration information of the synchronizationsignal burst set of a neighbor cell in the wireless system comprises anumber of the synchronization signal blocks actually transmitted in theneighbor cell and periodicity of the synchronization signal burst set.19. The method according to claim 12, wherein the additional systeminformation comprises an indication related to synchronizationinformation in the wireless system.
 20. The method according to claim 12wherein the one or more bits are included in a payload of the PBCH andwherein the one or more bits are the most significant bits of thepayload.
 21. The method according to claim 12 wherein the predefinedfrequency is 6 GHz.
 22. A terminal device in a wireless systemcomprising: a processor; and a memory, the memory containinginstructions which, when executed by the processor, cause the terminaldevice to: receive a physical broadcast channel (PBCH) including one ormore bits from a base station, wherein the one or more bits indicateadditional system information if a frequency of the wireless system iswithin a frequency range up to a predefined frequency and otherwiseindicate a location of a slot group comprising at least onesynchronization signal block in a synchronization signal burst setincluding the slot group; and obtain from the one or more bits thelocation of the slot group in the synchronization signal burst set orthe additional system information.
 23. The terminal device according toclaim 22, wherein the PBCH is interleaved with a downlink pilot signalsequence carrying one or more bits indicating a location of the at leastone synchronization signal block within the slot group; and theinstructions further cause the terminal device to obtain from thedownlink pilot signal sequence the location of the at least onesynchronization signal block within the slot group.